Three coordinated scientific conferences, collectively entitled "The Scientific Basis for the Public Health Control of Environmental Hazards" will be held from 6/21-30/78. The individual conferences are "Health Effects of Asbestos Exposure", "Health Effects of Halogenated Aromatic Hydrocarbons", and Public Health Control of Environmental Hazards". This format will provide an opportunity to examine and discuss a complex problem: Scientists are able, with increasing sophistication, to evaluate the hazards to health associated with the manufacture and utilization of industrial chemicals. But, at the same time, they share with society at large an inadequate understanding of how to make the regulatory decisions that would effectively deal wth the risks and benefits that accompany the use of these materials. While fulfilling a social need, an unknown number of these chemicals at the same time may pose a real threat to the health of the worker at the site of production and to the consumer at large. The halogenated aromatic hydrocarbons constitute a large group of chemicals which have found extensive application in the last several decades in our chemical, plastics and polymer industries. The recent discoveries concerning the health risks associated with their use has created wide-spread concern. This conference will examine what we now consider to be the hazards that result from human exposure to these chemicals, what we now know of their movement through the ecological chain, their contamination of the envronment and their long-term effects, especially with regard to human cancer.